A group of cells within one brain region may control the physical symptoms that plague people trying to kick their nicotine addiction.

In a new study, researchers laced mice’s water with nicotine and then took the drug away. In withdrawal, the mice shook, scratched and nodded their heads more than healthy animals. A close look at the drugged animals’ brains showed extra activity in cells within the interpeduncular nucleus, which sits right above the brain stem.